1. Field of the Invention
This invention relates in general to techniques for securing objects on shafts and in particular to techniques that allow removal or change in position without the use of tools.
2. Description of the Prior Art
There are many situations where it is desirable to secure objects in a given position on a shaft of given cross section quickly, securely, and without the use of tools. One such application is the ability to secure free weights on a barbell for weightlifting.
The Myhrman U.S. Pat. No. 4,646,398 shows a rotatably connected locking ring but requires costly machining techniques to manufacture. Also, locking ring radial clearance around the bar and the cam action of the locking lever need to be accurately determined for safe and positive locking action. Variations in shaft diameter are not easily accommodated.
The Polson U.S. Pat. No. 4,639,979 shows a radially operating clamping collar which uses a frictional material to avoid slipping on the bar. The clamp design does not allow for adjustment due to variation in bar diameter nor does it adjust to compensate for wear or variations in coefficient of friction of the lining material.
The Gall U.S. Pat. No. 4,585,367 shows a complicated and more costly arrangement of gear shapes which are not suited for use on the many barbells already in use or manufactured and in inventory available for sale.
The Weider U.S. Pat. No. 4,569,105 shows a spring-type weight retention device with a locking lever. This configuration does not readily adapt to changes in bar diameter, and the retention force is of fixed value for the given fit of spring device to bar. The force tending to push the weights off the end of the bar can eventually be increased to the point of sliding the spring clamp off the bar.
The Gogarty U.S. Pat. No. 4,529,197 shows a complex arrangement of machined parts which are not suited to barbells already in use or manufactured for sale.
The Miles U.S. Pat. No. 4,738,446 shows a complex arrangement of machined parts which are not suited to barbells already in use or manufactured for sale.
The Holman U.S. Pat. No. 2,815,778 Uses the concept of more than one "key" or tilting lock plate to secure a movable jaw on a frame. The very basic design of the lock plates makes it necessary to use multiple pieces and make them relatively long for proper locking and release.